Nice!
I'm actually planning something similar - DIY Fluke 734A, that is 4 LTZ1000 based 10V reference modules, each with 10K reference as well. For now I have all the parts for the 7V reference circuit and 10K resistors (VHP202Z) and I need to design the board. Once I finish that and the references will be aging I'll have plenty of time to figure out other circuits in the module (battery + power supply/charging, 7->10V step-up, mini-oven for VHP202Z 10K maybe, small signal relay to switch output between raw 7V and 10V, output protection etc.).
He must have excellent access to parts, all the oil filled Vishays, hermetic LT1013 and so on. Many months ago I requested a quote from Vishay, as I wanted to buy the LTZ1000 resistors and 10K reference (5 sets) and I got completely ignored, so I got second hand resistors (non-oil filled Vishays for LTZ1000 and VHP202Z) from eBay and the remaining parts (including LTZ1000 and LT1013 DIP8) from DigiKey.
Interesting power/voltage connection with the bare wires soldered between the mini-module and the base board. I've decided to go the 3458A reference module route and planned pin header connectors. Are bare wires better with respect to thermal EMF?